Portable two-way radio devices and two-way radio systems in general are utilized in a variety of organizations where near-instant communication is often critical, and monitoring the communication occurring among others in the organization allows collaboration and coordination. Some conventional two-way radios can only receive on one channel at a time. In recent years two-way radios have been designed to monitor a primary channel and monitor one or more other channels or talk groups, but they could still only receive on one channel at a time. More recently portable two-way radio devices have been designed with “dual watch” capability that allows simultaneous reception of two channels, with the audio for each channel being mixed together and played over a single speaker. Thus, dual watch radios allow a user to hear two different voices, including when they speak at the same time.
People often listen to multiple different voices at the same time in person. However, unlike in-person conversation, where our binaural sense of hearing helps to allows us to distinguish different conversations, and considering that transmitters band-limit voice signals and remove potentially distinctive audio spectral content, it is often very hard to distinguish between the voices of two audio streams being played over a single speaker. Simply making one stream louder can obscure the other voice stream and render it unintelligible. In fact, given the filtering that occurs at the transmitter, even when the speakers are not speaking at the same time it can be difficult to determine the identity of either the person speaking or the channel on which they are speaking.
Accordingly, there is a need for a method and apparatus for allowing a listener to be able to discriminate between two channels that are played over the same speaker.
Those skilled in the field of the present disclosure will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Well known elements, structure, or processes that would be necessary to practice the invention, and that would be well known to those of skill in the art, are not necessarily shown and should be assumed to be present unless otherwise indicated.